(codepipeline-actions): custom event for codepipeline codecommit actions

[matwerber1]

This feature request is to allow customization of the CloudWatch Event created by a CodeCommit source action in the aws-codepipeline-actions module.

Use Case

Per the blog post below, one may want to add custom logic to the CloudWatch Event that triggers a pipeline, so that they can selectively determine when to trigger a pipeline rather than triggering it on every commit to the branch being watched. This customization may be done by having the CloudWatch Event invoke a Lambda rather than directly triggering the pipeline. The Lambda can apply logic to determine whether this (or a different) pipeline is triggered.

Today, the aws-codepipeline-actions CodeCommit source action does not allow you to specify / modify the rules of the CloudWatch Event created by the construct.

Inspiration for this request is from the blog below:

https://aws.amazon.com/blogs/devops/adding-custom-logic-to-aws-codepipeline-with-aws-lambda-and-amazon-cloudwatch-events/

I want to use trunk-based development (single master branch) but have the ability to selectively trigger a pipeline based on facts about the commit.

For example:

1. If a README was the the only file changed, do not trigger the normal pipeline.

2. If (e.g. in the event of an emergency), I need to push a hotfix straight to prod while skipping my test and staging environment, I want to invoke a different pipeline that is source -> build -> prod, instead of my normal pipeline of source-> test -> staging -> prod.

Proposed Solution

Proposed idea #1 is to able to specify your own, previously-created CloudWatch Event, e.g.:

new codepipeline_actions.CodeCommitSourceAction({
          actionName: 'CodeCommit_Source',
          role: props.role,
          eventRole: props.eventRole,
          repository: props.repository,
          branch: props.branch,
          output: props.output,
          event: <YOUR CUSTOM EVENT>        // FEATURE REQUEST
        }),

Idea 2 is to be able to customize the target parameters of the event created by the source action:

new codepipeline_actions.CodeCommitSourceAction({
          actionName: 'CodeCommit_Source',
          role: props.role,
          eventRole: props.eventRole,
          repository: props.repository,
          branch: props.branch,
          output: props.output,
          eventTarget:    <custom Lambda resource>.        // FEATURE REQUEST
}),

Other

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[skinny85]

Thanks for the feature request @matwerber1 . This is a big feature, and I'm not sure I completely agree with the use cases you've outlined (for example, If a README was the the only file changed, do not trigger the normal pipeline. - that seems very dangerous to me).

However, if you want to work on it, I'm happy to offer guidance in getting this in 🙂.

[matwerber1]

I'm not 100% sure I agree with it either, but I have talked to some where it might make sense, and of course, the blog post suggests others may want to use the approach, too.

I can't promise I can find the time to work on it, but I'm not opposed to it. It would be fun to contribute to the CDK :) Is there a good starting point? My Typescript is not strong but may be a good learning opportunity.

[skinny85]

The Contributing.md file is a good start. You can also check out my blog post on the subject (shameless plug): https://www.endoflineblog.com/cdk-tips-02-how-to-contribute-to-the-cdk

[kaiz-io]

I just ran into this issue when trying to use a single source for hosting both CDK source and application source, while using CDK Pipelines for the continuous CDK deployment and AWS CodePipeline for Application deployment.

Everytime I update the CDK code it will fire both a build for CDK and app and vice versa. Unless this is a anti-pattern. I would imagine more people to have a issues as they adopt CDK Pipelines.

[Rofor51]

This is still relevant. Would be great to have if you want to create a scheduled build after a commit.

[adamtimmins]

With CDK Pipelines this would be a hugely helpful feature.

[jolo-dev]

@matwerber1 I think, I might have a solution for that:

Once you create the Pipeline, you can add (apparently not remove) events

const pipeline = new Pipeline(this, 'Pipeline');
const customLambdaTrigger = new Function(this, 'customLambdaTrigger', {
      /* your configs */
      initialPolicy: [
        new PolicyStatement({
          actions: ['codecommit:GetDifferences'],
          resources: [repository.repositoryArn],
        }),
        new PolicyStatement({
          actions: ['codepipeline:StartPipelineExecution'],
          resources: [pipeline.pipelineArn],
        }),
      ],
    });
const eventPattern
      = {
        'detail-type': ['CodeCommit Repository State Change'],
        'resources': [repository.repositoryArn],
        'source': ['aws.codecommit'],
        'detail': {
          referenceType: ['branch'],
          event: ['referenceCreated', 'referenceUpdated'],
          referenceName: ['main'],
        },
      };
pipeline.onEvent('EventTrigger', {
      eventPattern,
      description: 'Trigger the pipeline when a commit is pushed to the master branch',
      target: new LambdaFunction(customLambdaTrigger),
 });

You need to disable the default rules of CodeCommitSourceAction (manually).

CC: @skinny85

[github-actions]

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